the research literature is very clear on that, my own city of st. louis recently implemented such a program and experienced very substantial declines in gun violence where the program was implemented. so policy number one for reducing our largest gun violence problem, which is the problem of typically two young men in a dispute. one or both of whom are arms, one kills or severely injures the other. we do know how to reduce that problem. we're not going to eliminate it, but it's important to keep in mind that over the last two decades, firearm homicide notice united states has declined by roughly 50%. >> right, it is a huge success story. >> it is a huge success story. we don't know all the reasons for the decline. but in those places in which smart policing of the sort i described has been implemented we've seen reductions, not simply in gun violence but in other forms of criminal activity as well. >> how about policy number two? >> policy number two has to do with our other gun violence problem. the problem we've been talking about over the last fe